On Wed, Mar 16, 2016 at 02:08:47PM -0400, Murali Karicheri wrote: > Bjorn, > > Thanks for your quick response! Please see below some clarification > and follow up question. > > On 03/16/2016 12:45 PM, Bjorn Helgaas wrote: > 0x1000] > > > > Obviously if the host bridge doesn't support I/O port space, we will > > be unable to assign space for I/O BARs, so you will see errors like > > this. > > > > We may be able to improve the message and/or make this less noisy. > > Guenter Roeck looked at a similar issue a while ago, but it's not > > completely trivial: > > > > http://lkml.kernel.org/r/20150515172836.GA27797@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx > > > > The PCI core should check in pci_enable_device() whether all the > > device BARs have been assigned. If not, it should fail. But if a > > driver doesn't need I/O space, it can use pci_enable_device_mem() to > > indicate that it only needs the MEM BARs. That should succeed even if > > the I/O BARs aren't assigned. > > > > Bottom line, if you omit I/O space on your host bridge: > > > > - You will see annoying "no space for" and "failed to assign" messages > > - Drivers that don't need I/O ports should still work > > - It's far better to have the messages than it was to pretend that > > the host bridge supported I/O space when it really didn't. > > > >> [ 0.448813] pci 0000:01:00.0: BAR 6: assigned [mem 0x60100000-0x6010ffff pref] > >> [ 0.448822] pci 0000:01:00.0: BAR 5: assigned [mem 0x60000000-0x600001ff] > >> [ 0.448834] pci 0000:01:00.0: BAR 4: no space for [io size 0x0010] > >> [ 0.448841] pci 0000:01:00.0: BAR 4: failed to assign [io size 0x0010] > >> [ 0.448848] pci 0000:01:00.0: BAR 0: no space for [io size 0x0008] > >> [ 0.448855] pci 0000:01:00.0: BAR 0: failed to assign [io size 0x0008] > >> [ 0.448863] pci 0000:01:00.0: BAR 2: no space for [io size 0x0008] > >> [ 0.448870] pci 0000:01:00.0: BAR 2: failed to assign [io size 0x0008] > >> [ 0.448877] pci 0000:01:00.0: BAR 1: no space for [io size 0x0004] > >> [ 0.448884] pci 0000:01:00.0: BAR 1: failed to assign [io size 0x0004] > >> [ 0.448891] pci 0000:01:00.0: BAR 3: no space for [io size 0x0004] > >> [ 0.448898] pci 0000:01:00.0: BAR 3: failed to assign [io size 0x0004] > >> [ 0.448907] pci 0000:00:00.0: PCI bridge to [bus 01] > >> > >> > >> The original log is below and even with the error, I am able to have SATA > >> drive function as expected over this PCIe interface. > >> > >> > >> [ 0.420648] PCI host bridge /soc/pcie@21020000 ranges: > >> [ 0.420659] No bus range found for /soc/pcie@21020000, using [bus 00-ff] > >> [ 0.420679] IO 0x23260000..0x400023263fff -> 0x00000000 > >> [ 0.420685] Requested IO range too big, new size set to 64K > >> [ 0.420702] MEM 0x60000000..0x6fffffff -> 0x60000000 > >> [ 0.420713] keystone-pcie 21021000.pcie: error -22: failed to map resource [io 0x0000-0x400000003fff] > >> [ 0.431849] keystone-pcie 21021000.pcie: PCI host bridge to bus 0000:00 > >> [ 0.431861] pci_bus 0000:00: root bus resource [bus 00-ff] > >> [ 0.431870] pci_bus 0000:00: root bus resource [io 0x0000-0x400000003fff] > > > > This range is obviously bogus, since it's way too big and not a nice > > round size. I guess this is what you're fixing. > > Yes. But from your response, I gather it is better to remove the bogus range. > I removed the range, and did a read/write test to the hard drive connected > to the Marvel SATA that is hooked to the PCIe interface and it still work > without issues. If your bridge doesn't support I/O space, you should definitely remove the range. I'm curious about this Marvell SATA device, though. It is this device? pci 0000:01:00.0: [1b4b:9182] type 00 class 0x010601 pci 0000:01:00.0: reg 0x10: [io 0x8000-0x8007] pci 0000:01:00.0: reg 0x14: [io 0x8040-0x8043] pci 0000:01:00.0: reg 0x18: [io 0x8100-0x8107] pci 0000:01:00.0: reg 0x1c: [io 0x8140-0x8143] pci 0000:01:00.0: reg 0x20: [io 0x800000-0x80000f] pci 0000:01:00.0: reg 0x24: [mem 0x00900000-0x009001ff] pci 0000:01:00.0: reg 0x30: [mem 0xd0000000-0xd000ffff pref] If so, it looks like it uses the drivers/ata/ahci.c driver, which uses pcim_enable_device(), which should require all BARs to be assigned. (It doesn't look like there is a pcim_enable_device_mem() variant.) But if you're on an arm or arm64 platform and you have PCI_PROBE_ONLY set, pcibios_enable_device() doesn't check whether resources are assigned, so the problem would be masked. We're trying to remove PCI_PROBE_ONLY, or at least remove it from paths like this, so this might become a problem soon. This might be a reason to add a pcim_enable_device_mem() interface that ahci_init_one() could use. It looks like ahci_init_one() doesn't actually depend on the I/O BAR. > Another thing to worry about is the customers who are using custom > fpga pci devices connected to the pcie bus and presently using > pci_enable_device() in their driver. So I guess if they fix their driver > to use pci_enable_device_mem() instead, it should continue to work > without issues, right? Yes. If the FPGA PCI devices don't have I/O BARs, it doesn't matter whether the driver uses pci_enable_device() or pci_enable_device_mem(). If the device has an I/O BAR, but the driver doesn't need it, the driver should use pci_enable_device_mem(). That will make it more portable. Bjorn -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
